Passive cooling system and method for electronics devices

ABSTRACT

An apparatus for passively cooling electronics. The apparatus for passively cooling electronics includes at least one heat pipe and at least one heat sink thermally coupled to a bridge plate. When a cradle is thermally coupled to the at least one heat pipe, the at least one heat sink draws heat from the cradle.

BACKGROUND

The present disclosure relates generally to the field of passive coolingand more particularly to passive cooling of electronics devices.

Legacy electronics device cooling technologies typically use a forcedair cooling method to remove heat from the electronics device. Morerecently, advanced cooling methods, such as water cooling and phasecooling systems, have been explored. However, there are many issues, forexample with installation and maintenance, that arise from the use ofthese systems in electronics devices.

The majority of existing systems depend on a forced air cooling method,i.e. fans. In existing systems, fans are used to directly coolprocessors and other internal components. Fans suffer from multipledeficiencies. For example, fans require significant physical space, arenoisy because of high RPMs, require a significant ventilation space,produce heat as they are working to reduce heat, and consume vastamounts of power to operate. Additionally, the manufacturing process bywhich the majority of fans are made in some instances may use harmfulindustrial chemicals that could be reactivated as the temperature of afan's blades increases thereby releasing these chemicals into exposedenvironments. Thus, there are high costs as well as potential health andenvironmental issues associated with operating fan-based systems. Often,data centers are designed for more wattage then necessary in order toaccount for necessary, but inefficient cooling systems. In addition,fan-based systems are prone to failure due to accumulation of dust,motor malfunction or burn-out thereby increasing operational andmaintenance costs. When over-heating occurs components sufferirreversible damage, increasing cost, power consumption, andenvironmental impact.

Liquid cooling systems are two systems in one. Liquid cooling systemsare greatly limited in their cooling capacity, depending on theconfiguration of the electronics device. Liquid cooling systems requireheat exchangers such as a radiator. As a result, liquid cooling systemsstill require fans to cool the radiator and other components notattached to a heat exchanger thereby supplanting the inefficiency of aforced air cooling system with a potentially dangerous and costly liquidcooling system still reliant on fans. Liquid cooling systems requiresignificant physical space, are complicated, are noisy because ofradiator fans, require a significant ventilation space, produce heat asthey are working to reduce heat, and consume vast amounts of power tooperate and maintain. The end user must devote significant time andeffort to set-up and maintain a liquid cooling system.

Moreover, the proximity of cooling liquid with electronics is apotential safety risk. Because components produce a lot of heat, thetubing typically used is constantly expanding and contracting causingthe tubes to fail and leak cooling solution, which can result inelectrical shorts and irreparable internal damage.

Phase cooling involves using a compressor system to cool electronics.Phase cooling typically only cools the CPU so fans are still needed tocool other components. The fans and compressor make a significant amountof noise, require extensive maintenance, and consume a significantamount of power. Operating a phase cooling system requires a high degreeof technical proficiency.

Thus, improved cooling systems and techniques are needed.

SUMMARY

A representative embodiment relates to an apparatus for passivelycooling electronics. The apparatus for passively cooling electronicsincludes at least one heat pipe and at least one heat sink thermallycoupled to a bridge plate. When a cradle is thermally coupled to the atleast one heat pipe, the at least one heat sink draws heat from thecradle.

Another representative embodiment relates to a method for passivelycooling electronics. The method includes drawing heat from an electroniccomponent through a cradle to at least one heat pipe. The heat from theat least one heat pipe is drawn to at least one heat sink through abridge plate and is dissipated.

Another representative embodiment relates to an apparatus for passivelycooling electronics. The apparatus for passively cooling electronicsincludes a cradle configured to thermally couple at least one heat pipeand an electronic component. The apparatus for passively coolingelectronics also includes a clamping mechanism configured to enhance thethermal coupling of the cradle to the at least one heat pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a passive cooling system in accordancewith a representative embodiment.

FIG. 2 is an exploded view of the passive cooling system of FIG. 1 inaccordance with a representative embodiment.

FIG. 3 is a top view of the passive cooling system of FIG. 2 inaccordance with a representative embodiment.

FIG. 4 is a perspective view of the device module of FIG. 2 inaccordance with a representative embodiment.

FIG. 5A-5F are diagrams of representative heat pipe topologies inaccordance with a representative embodiment.

FIG. 6 is an exploded view of the heat pipe assembly of FIG. 2 inaccordance with a representative embodiment.

FIG. 7 is a diagram of the bridge plate of FIG. 6 in accordance with arepresentative embodiment.

FIG. 8 is a perspective view of the processor heat pipe assembly of FIG.2 in accordance with a representative embodiment.

DETAILED DESCRIPTION

A passive cooling system and method for electronics devices aredescribed. In the following description, for purposes of explanation,numerous specific details are set forth to provide a thoroughunderstanding of representative embodiments of the invention. It will beevident, however, to one skilled in the art that the representativeembodiments may be practiced without these specific details. Thedrawings are not to scale. In other instances, well-known structures anddevices are shown in simplified form to facilitate description of therepresentative embodiments.

Referring to FIG. 1, a perspective view of a passive cooling system 100in accordance with a representative embodiment is shown. In anembodiment, the passive cooling system 100 is configured as a rack-mountchassis. The passive cooling system 100 includes a front panel 110, adrive bay 120, a cover 130, heat sinks 140, filler strip 150, and amedia drive 160. The front panel 110 includes holes 113 for mounting thepassive cooling system 100 to a rack (not shown). The rack can be a 19inch rack, a 23 inch rack, a half rack, or any other size or depth rack.Likewise, non-rack configurations are possible. Additionally, the holes113 can include quick connects, rails, or other fasteners. The frontpanel 110 also includes handles 115 for moving the passive coolingsystem 100 and a latch 111 for securing bay doors 125 that cover thedrive bay 120. The media drive 160 can be, for example, a compact disc(CD) burner or a tape drive.

The passive cooling system 100 can be any height or depth. Inparticular, the drive bay 120 can be a 1 unit, 2 unit, 4 unit, 8 unit,or 16 unit bay. The bays can be configured in various configurationssuch as horizontal or vertical. Additionally, the passive cooling system100 can include other input devices such as removable media drives,keyboards, displays, mice, or joysticks. Alternatively, the passivecooling system 100 can be a programmable logic controller chassis, ablade chassis, a VMEbus-type enclosure, a PCI-type enclosure, aCompactPCI-type enclosure, a server, or any other electronic device withmodular bays and/or sub-bays. The passive cooling system 100 can also bea desktop computer, a tower computer, an all-in-one system where thedisplay is integrated, an appliance, or a mobile platform such as alaptop.

Referring to FIG. 2, an exploded view of the passive cooling system 100of FIG. 1 in accordance with a representative embodiment is shown. Thepassive cooling system 100 includes a front panel 110, a cover 130, heatsinks 140, filler strip 150, and a media drive 160. The front panel 110includes handles 115 and a latch 111 for securing bay doors 125 thatcover the drive bay. The passive cooling system 100 also includes a heatpipe assembly 210, a device module 220, a processor heat pipe assembly230, a motherboard 260, a daughterboard 250, a bottom 270, and a backpanel 280. The front panel 110, the cover 130, heat sinks 140, fillerstrip 150, the bottom 270, and the back panel 280 constitute theenclosure of the passive cooling system 100.

The device module 220 includes a cradle assembly and an electroniccomponent. Preferably, the electronic component is a hot-swappablenon-volatile storage device such as a hard drive. Alternatively, theelectronic component can be any electronic device; for example, a 3.5″hard drive, a 2.5″ hard drive, a 5.25″ drive, an optical drive, a tapedrive, solid state drive, a card reader, a memory bank, a magneticmemory bank, a communications module, a daughterboard, a sensor module,or an input/output module. The electronic component is thermally coupledto the cradle assembly. The cradle assembly draws heat away from theelectronic component. The passive cooling system 100 can include aplurality of device modules. The cradle assembly can also include aclamping or securing mechanism as described in more detail below.

The device module 220 is removably mounted on the heat pipe assembly 210via the cradle assembly. The device module 220 is thermally coupled tothe heat pipe assembly 210. The heat pipe assembly 210 is thermallycoupled to the heat sinks 140 and filler strip 150. The heat pipeassembly 210 draws heat from the device module 220. The heat sinks 140draw heat from the heat pipe assembly 210. Each of the thermal couplingswhere two separate pieces meet can include a thermal compound to enhancethe thermal characteristics of the junction. Alternatively, the heatpipe assembly 210, heat sinks 140 and filler strip 150 can be one piecethat is thermally continuous. The heat pipe assembly 210 can alsoinclude electrical connections for the electronic component. The heatpipe assembly 210 is described in more detail below.

The electronic component of device module 220 is electrically connectedto the motherboard 260. The motherboard 260 can also includedaughterboard 250 which can be, for example, a video card, an Ethernetcard, a processor card, or any other computer card. The motherboard 260controls the device module 220 and daughterboard 250. The motherboard260 can be powered through the rack to which the passive cooling system100 is mounted. The motherboard 260 includes one or more processorswhich are thermally coupled to the heat sinks 140 by processor heat pipeassembly 230. Alternatively, other devices of the motherboard 260 anddaughterboard 250, for example, a power supply, can also be thermallycoupled to the heat sinks 140. Advantageously, the passive coolingsystem 100 provides effective cooling to the device module 220 andprocessors of the motherboard 260 without the use of a fan or liquidcooling system, and without the need for additional power or costlymaintenance.

Referring to FIG. 3, a top view of the passive cooling system 100 ofFIG. 2 in accordance with a representative embodiment is shown. Theblock arrows depict the main thermal paths through which heat cantravel. The passive cooling system 100 includes a front panel 110, heatsinks 140, filler strips 150, a heat pipe assembly 210, device modules220, a processor heat pipe assembly 230, a motherboard 260, a memorymodule 310, and a power supply heat pipe assembly 320.

As device modules 220 generate heat, heat pipe assembly 210 draws heataway from the drive modules 220. The filler strips 150 draw heat awayfrom the heat pipe assembly 210. Finally, the heat sinks 140 draw heataway from the filler strips 150 and dissipate the heat into the ambientatmosphere. Thus, the heat sinks 140, filler strips 150, heat pipeassembly 210, and device modules 220 form an open-loop cooling system.

As a processor (not shown) of the motherboard 260 generates heat,processor heat pipe assembly 230 draws heat away from the processor. Theheat sinks 140 draw heat away from the processor heat pipe assembly 230.Likewise, as a power supply (not shown) of the motherboard 260 generatesheat, power supply heat pipe assembly 320 draws heat away from theprocessor. The heat sinks 140 draw heat away from the power supply heatpipe assembly 320. In some cases, components do not need additionalcooling. For example, memory module 310 can be cooled by the ambientatmosphere. Advantageously, the passive cooling system 100 provideseffective cooling to the device module 220, processor and power supplywithout the use of a fan or liquid cooling system.

Referring to FIG. 4, a perspective view of the device module 220 of FIG.2 in accordance with a representative embodiment is shown. The devicemodule 220 includes a cradle assembly 410 and an electronic component420. The electronic component 420 is fastened to the cradle assembly410. The electronic component 420 can be a non-volatile storage device,such as a hard disc drive, as described above. The cradle assembly 410can be both a thermal sink and a docking mechanism for the electroniccomponent 420. The cradle assembly 410 can be made of metal, or anythermally conductive material. Preferably, the cradle assembly 410 ismade of aluminum or copper alloy. The cradle assembly 410 can bemachined, cast, or extruded. Heat spreaders can be embedded in thecradle assembly 410. A thermal compound can be applied to the spacebetween the electronic component 420 and the cradle assembly 410.

The cradle assembly 410 includes heat pipe conduits 430. The cradleassembly 410 is docked on heat pipes that match heat pipe conduits 430.The cradle assembly 410 can have one or a plurality of heat pipeconduits 430. The heat pipe conduits 430 are disposed on either side ofthe electronic component 420. Alternatively, the heat pipe conduits 430can be located near a primary heat source of the electronic component420. The heat pipe conduits 430 can be 1.5 inches or smaller in diameterdepending on the application; however, larger conduits are alsopossible. For example, the heat pipe conduits 430 can range from 1.5inches to 0.25 inches in diameter. Additionally, the heat pipe conduits430 can each be a different size. For example, a heat conduit/heat pipelocated towards the center of an enclosure can be larger than a heatconduit/heat pipe located towards the outside of the enclosure. The heatpipe conduits 430 include clamping slots 440 which can be used to changethe size of the heat pipe conduits 430.

The clamping slots 440 are associated with a clamping mechanism 450.When a clamping lever 460 is pressed in, the clamping mechanism 450closes the clamping slots 440 thereby tightening the heat pipe conduits430. The clamping action creates a better thermal coupling between thecradle assembly 410 and its associated heat pipes. Additionally, theclamping action fastens the cradle assembly 410 to the heat pipes sothat the cradle assembly 410 cannot move and maintain thermalcontinuity. Thus, the cradle assembly 410 can be quickly removed andreplaced. Alternatively, many other clamping and/or attachmentmechanisms are possible.

Referring to FIG. 5A-5F, diagrams of representative heat pipe topologiesin accordance with a representative embodiment are shown. As shown inFIG. 5A, a heat pipe 510 can be circular. As shown in FIG. 5B, a heatpipe 520 can have fingers that press into the side of cradle assembly525. As shown in FIG. 5C, a heat pipe 530 can have fins to increasesurface area. As shown in FIG. 5D, a heat pipe 540 can be square and bepressed between cradle assembly 547 and a separate batten 545. As shownin FIG. 5E, a heat pipe 550 can be triangular. As shown in FIG. 5F, aheat pipe 560 can be circular and be pressed between cradle assembly 567and a separate batten 565.

Referring to FIG. 6, an exploded view of the heat pipe assembly 210 ofFIG. 2 in accordance with a representative embodiment is shown. The heatpipe assembly 210 includes a bridge plate 610, a back plane printedcircuit board (PCB) 620, and heat pipes 630. The heat pipes 630 arecoupled to the bridge plate 610 through the back plane PCB 620. Thebridge plate 610 is coupled to filler strips 150 by screws 655. Athermal compound can be applied to the space between the bridge plate610 and the filler strips 150.

The bridge plate 610 can be both a thermal sink and a dock for devicemodule 220. The bridge plate 610 can be made of metal or any thermallyconductive material. In some implementations, the bridge plate 610 ismade of an aluminum or copper alloy. The bridge plate 610 can bemachined, cast, stamped or extruded. Heat spreaders can be embedded inthe bridge plate 610. The bridge plate 610 includes a series of tapholes for heat pipes 630. Alternatively, the heat pipes 630 can befastened to the bridge plate 610 by pressing or other fastening meansthat provide a good thermal connection. A thermal compound can beapplied to the space between the bridge plate 610 and the heat pipes630.

The device module 220 slides over a pair of heat pipes 630. The heatpipes 630 are tapered at one end to make sliding the device module 220onto the heat pipes 630 easy. The heat pipes 630 can range from 1.5inches or less in diameter depending on the application. The heat pipes630 are arranged so that when a device module is mounted, the heat pipes630 are disposed on either side of the device module. Alternatively, theheat pipes 630 can be arranged in various configurations around a devicemodule such as on the top and bottom. The heat pipes 630 can be made ofmetal or any thermally conductive material. Preferably, the heat pipes630 are made of thermally conductive material, such as copper alloy oraluminum. The heat pipes 630 can also be plated to prevent oxidation.The heat pipes 630 can be machined, cast, stamped or extruded. In use, athermal compound can be applied to the surface of the heat pipes 630 topromote thermal conductivity to an associated device module 220 and toreduce oxidation. When the clamping mechanism of the device module 220is set, the cradle assembly of the device module 220 presses against theassociated heat pipes 630 creating a thermal and physical connection.

The back plane PCB 620 includes the power and data connections for thedevice module 220. The back plane PCB 620 is connected to themotherboard of the electronics device. Thus, the device module 220 canbe easily electrically connected to the motherboard. The back plane PCB620 is a custom PCB designed to fit around the heat pipes 630. The backplane PCB 620 includes connections appropriate for the particular kindof electronic component associated with the device module 220. Forexample, where the device module 220 is mounted with a hard disk, theback plane PCB 620 includes power and serial ATA, EIDE, IDE, or SCSIconnectors. Thus, when a user inserts device module into a bay, thedevice module engages a power connector and a data connector. When theuser engages the clamping mechanism, the device module becomes locked inplace. The clamping mechanism can be designed to actively engage theconnectors on the back plane PCB 620.

Referring to FIG. 7, a diagram of the bridge plate 610 of FIG. 6 inaccordance with a representative embodiment is shown. The bridge plate610 includes heat spreaders 710 for each set of heat pipes. In oneimplementation, the bridge plate 610 is aluminum and the heat spreader710 is made of copper alloy. The heat spreader 710 is located inside ofthe bridge plate 610. The bridge plate 610 also includes holes 720 whichare used to attach the heat pipes. The holes 720 go through the heatspreader 710 so that when the heat pipes are attached, there is a directthermal connection between the heat pipes and the heat spreader 710. Theheat spreader 710 increases the thermal transfer efficiency of thebridge plate 610 by directing the thermal flow. In this example, theheat spreaders 710 are doughnut shaped. Alternatively, the heat spreadercould run horizontally as well as other configurations.

Referring to FIG. 8, a perspective view of the processor heat pipeassembly 230 of FIG. 2 in accordance with a representative embodiment isshown. Motherboard 260 includes processors 810. A first thermal mass 820is attached to each of the processors 810. The first thermal masses 820are thermally coupled to second thermal masses 840 by heat pipes 830.The second thermal masses 840 are each thermally coupled to a heat sink140. A thermal compound can be applied between the first thermal masses820 and the processors; and the second thermal masses 840 and the heatsinks 140.

As the processors produce heat, the first thermal masses 820 draw heatfrom the processors. The second thermal masses 840 draw heat from thefirst thermal masses 820 through heat pipes 830. The heat sinks 140 drawheat from the second thermal masses 840. Finally, the heat sinks 140dissipate the heat into the ambient air. Advantageously, the passivecooling system provides effective cooling to processors without the useof fans or a liquid cooling system.

The foregoing description of the representative embodiments have beenpresented for purposes of illustration and of description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed, and modifications and variations are possible in light of theabove teachings or may be acquired from practice of the invention. Forexample, the described representative embodiments focused on arepresentative implementation of a horizontal drive configuration on arack-mount server. The present invention, however, is not limited to arepresentative implementation as described and depicted. Those skilledin the art will recognize that the device and methods of the presentinvention may be practiced using various combinations of components.Additionally, the device and method may be adapted for differentelectronics systems that need to be cooled. The embodiments were chosenand described in order to explain the principles of the invention and aspractical applications of the invention to enable one skilled in the artto utilize the invention in various embodiments and with variousmodifications as suited to the particular use contemplated. It isintended that the scope of the invention be defined by the claimsappended hereto and their equivalents.

1. An apparatus for passively cooling electronics comprising: at leastone heat pipe thermally coupled to a bridge plate; and at least one heatsink thermally coupled to the bridge plate, wherein when a cradle isthermally coupled to the at least one heat pipe, the at least one heatsink draws heat from the cradle.
 2. The apparatus of claim 1, furthercomprising the cradle thermally coupled to the at least one heat pipeand an electronic component, wherein the cradle is thermally coupled tothe at least one heat pipe by at least one heat pipe conduit.
 3. Theapparatus of claim 2, wherein the cradle comprises a clamping mechanismconfigured to enhance the thermal coupling of the cradle to the at leastone heat pipe.
 4. The apparatus of claim 1, wherein bridge platecomprises an aluminum alloy.
 5. The apparatus of claim 4, wherein bridgeplate comprises a heat spreader.
 6. The apparatus of claim 5, whereinthe heat spreader comprises a copper alloy.
 7. The apparatus of claim 1,further comprising a printed circuit board coupled to the bridge plateand configured to electronically connect to an electronic componentassociated with the cradle.
 8. The apparatus of claim 7, wherein theelectronic component comprises a non-volatile storage device.
 9. Theapparatus of claim 1, wherein the at least one heat pipe has a diameterin a range from 1.5 inches or less.
 10. The apparatus of claim 1,wherein the at least one heat pipe comprises a copper alloy.
 11. Theapparatus of claim 1, further comprising an enclosure configured to beattached to a rack chassis.
 12. The apparatus of claim 1, furthercomprising a first thermal compound between the at least one heat pipethe bridge plate, and a second thermal compound between the at least oneheat sink and the bridge plate.
 13. A method for passively coolingelectronics comprising: drawing heat from an electronic componentthrough a cradle to at least one heat pipe; drawing the heat from the atleast one heat pipe to at least one heat sink through a bridge plate;and dissipating the heat.
 14. The method of claim 13, wherein the cradlethermally couples the electronic component to the at least one heatpipe.
 15. The method of claim 13, wherein the cradle comprises aclamping mechanism configured to enhance the thermal coupling of thecradle to the at least one heat pipe.
 16. An apparatus for passivelycooling electronics comprising: a cradle configured to thermally coupleat least one heat pipe and an electronic component; and a clampingmechanism configured to enhance the thermal coupling of the cradle tothe at least one heat pipe.
 17. The apparatus of claim 16, wherein thecradle comprises an aluminum alloy.
 18. The apparatus of claim 16,further comprising at least one heat pipe conduit associated with the atleast one heat pipe.
 19. The apparatus of claim 16, wherein theelectronic component is a non-volatile storage device.
 20. The apparatusof claim 19, wherein the non-volatile storage device is hot swappable.